| 摘要 |
PURPOSE:To enable a data terminal equipment to confirm the transmission/ reception of data by comparing transmission data transmitted from the data terminal equipment with reception data returned from the master station during the master station's operation of collecting data from the data terminal equipment. CONSTITUTION:Upon receiving a polling signal transmitted from the master station 1, the data terminal equipment 3 transmits the data signal of parallel data from its central processing unit 31 to its serial input/output circuit 32 where the data is converted to serial data, then this data is transmitted to a transmission line 2 via a modem 33. In response to this, the data signal of serial data is returned from the master station 1. This data signal enters the modem 33 from the transmission line 2, converted to parallel data in the circuit 32, and is fetched by the central processing circuit 31. The circuit collates the transmitted data signal with the data signal returned from the master station 1 and received by the self-equipment through a data collation circuit 34, and decide the transmission line 2 to be normal, if they coincide with each other, but decide to be abnormal in the event of noncoincidence. |
